Optical modules are commonly used in consumer electronic devices. For example, almost all current portable telephones and computers include a miniature camera module. Miniature optical projection modules are also coming into increasing use in portable consumer devices for a variety of purposes.
Such projection modules may be used, for example, to cast a pattern of structured light onto an object for purposes of 3D mapping (also known as depth mapping). In some systems of this sort a light source, such as a laser diode or LED, transilluminates a transparency with optical radiation so as to project a pattern onto the object. (The terms “optical” and “light” as used in the present description and in the claims refer generally to any and all of visible, infrared, and ultraviolet radiation.) An image capture assembly captures an image of the pattern that is projected onto the object, and a processor processes the image so as to reconstruct a three-dimensional (3D) map of the object.
Optical projectors may, in some applications, project light through one or more diffractive optical elements (DOEs). In some cases two DOEs can be used together to diffract an input beam while reducing the energy in the zero-order (undiffracted) beam. The DOEs may be mechanically sealed to a substrate to help protect and ensure their integrity.